dmi_scan: fix missing check for _DMI_ signature in smbios_present()
[linux-2.6.git] / drivers / firmware / dmi-sysfs.c
1 /*
2  * dmi-sysfs.c
3  *
4  * This module exports the DMI tables read-only to userspace through the
5  * sysfs file system.
6  *
7  * Data is currently found below
8  *    /sys/firmware/dmi/...
9  *
10  * DMI attributes are presented in attribute files with names
11  * formatted using %d-%d, so that the first integer indicates the
12  * structure type (0-255), and the second field is the instance of that
13  * entry.
14  *
15  * Copyright 2011 Google, Inc.
16  */
17
18 #include <linux/kernel.h>
19 #include <linux/init.h>
20 #include <linux/module.h>
21 #include <linux/types.h>
22 #include <linux/kobject.h>
23 #include <linux/dmi.h>
24 #include <linux/capability.h>
25 #include <linux/slab.h>
26 #include <linux/list.h>
27 #include <linux/io.h>
28
29 #define MAX_ENTRY_TYPE 255 /* Most of these aren't used, but we consider
30                               the top entry type is only 8 bits */
31
32 struct dmi_sysfs_entry {
33         struct dmi_header dh;
34         struct kobject kobj;
35         int instance;
36         int position;
37         struct list_head list;
38         struct kobject *child;
39 };
40
41 /*
42  * Global list of dmi_sysfs_entry.  Even though this should only be
43  * manipulated at setup and teardown, the lazy nature of the kobject
44  * system means we get lazy removes.
45  */
46 static LIST_HEAD(entry_list);
47 static DEFINE_SPINLOCK(entry_list_lock);
48
49 /* dmi_sysfs_attribute - Top level attribute. used by all entries. */
50 struct dmi_sysfs_attribute {
51         struct attribute attr;
52         ssize_t (*show)(struct dmi_sysfs_entry *entry, char *buf);
53 };
54
55 #define DMI_SYSFS_ATTR(_entry, _name) \
56 struct dmi_sysfs_attribute dmi_sysfs_attr_##_entry##_##_name = { \
57         .attr = {.name = __stringify(_name), .mode = 0400}, \
58         .show = dmi_sysfs_##_entry##_##_name, \
59 }
60
61 /*
62  * dmi_sysfs_mapped_attribute - Attribute where we require the entry be
63  * mapped in.  Use in conjunction with dmi_sysfs_specialize_attr_ops.
64  */
65 struct dmi_sysfs_mapped_attribute {
66         struct attribute attr;
67         ssize_t (*show)(struct dmi_sysfs_entry *entry,
68                         const struct dmi_header *dh,
69                         char *buf);
70 };
71
72 #define DMI_SYSFS_MAPPED_ATTR(_entry, _name) \
73 struct dmi_sysfs_mapped_attribute dmi_sysfs_attr_##_entry##_##_name = { \
74         .attr = {.name = __stringify(_name), .mode = 0400}, \
75         .show = dmi_sysfs_##_entry##_##_name, \
76 }
77
78 /*************************************************
79  * Generic DMI entry support.
80  *************************************************/
81 static void dmi_entry_free(struct kobject *kobj)
82 {
83         kfree(kobj);
84 }
85
86 static struct dmi_sysfs_entry *to_entry(struct kobject *kobj)
87 {
88         return container_of(kobj, struct dmi_sysfs_entry, kobj);
89 }
90
91 static struct dmi_sysfs_attribute *to_attr(struct attribute *attr)
92 {
93         return container_of(attr, struct dmi_sysfs_attribute, attr);
94 }
95
96 static ssize_t dmi_sysfs_attr_show(struct kobject *kobj,
97                                    struct attribute *_attr, char *buf)
98 {
99         struct dmi_sysfs_entry *entry = to_entry(kobj);
100         struct dmi_sysfs_attribute *attr = to_attr(_attr);
101
102         /* DMI stuff is only ever admin visible */
103         if (!capable(CAP_SYS_ADMIN))
104                 return -EACCES;
105
106         return attr->show(entry, buf);
107 }
108
109 static const struct sysfs_ops dmi_sysfs_attr_ops = {
110         .show = dmi_sysfs_attr_show,
111 };
112
113 typedef ssize_t (*dmi_callback)(struct dmi_sysfs_entry *,
114                                 const struct dmi_header *dh, void *);
115
116 struct find_dmi_data {
117         struct dmi_sysfs_entry  *entry;
118         dmi_callback            callback;
119         void                    *private;
120         int                     instance_countdown;
121         ssize_t                 ret;
122 };
123
124 static void find_dmi_entry_helper(const struct dmi_header *dh,
125                                   void *_data)
126 {
127         struct find_dmi_data *data = _data;
128         struct dmi_sysfs_entry *entry = data->entry;
129
130         /* Is this the entry we want? */
131         if (dh->type != entry->dh.type)
132                 return;
133
134         if (data->instance_countdown != 0) {
135                 /* try the next instance? */
136                 data->instance_countdown--;
137                 return;
138         }
139
140         /*
141          * Don't ever revisit the instance.  Short circuit later
142          * instances by letting the instance_countdown run negative
143          */
144         data->instance_countdown--;
145
146         /* Found the entry */
147         data->ret = data->callback(entry, dh, data->private);
148 }
149
150 /* State for passing the read parameters through dmi_find_entry() */
151 struct dmi_read_state {
152         char *buf;
153         loff_t pos;
154         size_t count;
155 };
156
157 static ssize_t find_dmi_entry(struct dmi_sysfs_entry *entry,
158                               dmi_callback callback, void *private)
159 {
160         struct find_dmi_data data = {
161                 .entry = entry,
162                 .callback = callback,
163                 .private = private,
164                 .instance_countdown = entry->instance,
165                 .ret = -EIO,  /* To signal the entry disappeared */
166         };
167         int ret;
168
169         ret = dmi_walk(find_dmi_entry_helper, &data);
170         /* This shouldn't happen, but just in case. */
171         if (ret)
172                 return -EINVAL;
173         return data.ret;
174 }
175
176 /*
177  * Calculate and return the byte length of the dmi entry identified by
178  * dh.  This includes both the formatted portion as well as the
179  * unformatted string space, including the two trailing nul characters.
180  */
181 static size_t dmi_entry_length(const struct dmi_header *dh)
182 {
183         const char *p = (const char *)dh;
184
185         p += dh->length;
186
187         while (p[0] || p[1])
188                 p++;
189
190         return 2 + p - (const char *)dh;
191 }
192
193 /*************************************************
194  * Support bits for specialized DMI entry support
195  *************************************************/
196 struct dmi_entry_attr_show_data {
197         struct attribute *attr;
198         char *buf;
199 };
200
201 static ssize_t dmi_entry_attr_show_helper(struct dmi_sysfs_entry *entry,
202                                           const struct dmi_header *dh,
203                                           void *_data)
204 {
205         struct dmi_entry_attr_show_data *data = _data;
206         struct dmi_sysfs_mapped_attribute *attr;
207
208         attr = container_of(data->attr,
209                             struct dmi_sysfs_mapped_attribute, attr);
210         return attr->show(entry, dh, data->buf);
211 }
212
213 static ssize_t dmi_entry_attr_show(struct kobject *kobj,
214                                    struct attribute *attr,
215                                    char *buf)
216 {
217         struct dmi_entry_attr_show_data data = {
218                 .attr = attr,
219                 .buf  = buf,
220         };
221         /* Find the entry according to our parent and call the
222          * normalized show method hanging off of the attribute */
223         return find_dmi_entry(to_entry(kobj->parent),
224                               dmi_entry_attr_show_helper, &data);
225 }
226
227 static const struct sysfs_ops dmi_sysfs_specialize_attr_ops = {
228         .show = dmi_entry_attr_show,
229 };
230
231 /*************************************************
232  * Specialized DMI entry support.
233  *************************************************/
234
235 /*** Type 15 - System Event Table ***/
236
237 #define DMI_SEL_ACCESS_METHOD_IO8       0x00
238 #define DMI_SEL_ACCESS_METHOD_IO2x8     0x01
239 #define DMI_SEL_ACCESS_METHOD_IO16      0x02
240 #define DMI_SEL_ACCESS_METHOD_PHYS32    0x03
241 #define DMI_SEL_ACCESS_METHOD_GPNV      0x04
242
243 struct dmi_system_event_log {
244         struct dmi_header header;
245         u16     area_length;
246         u16     header_start_offset;
247         u16     data_start_offset;
248         u8      access_method;
249         u8      status;
250         u32     change_token;
251         union {
252                 struct {
253                         u16 index_addr;
254                         u16 data_addr;
255                 } io;
256                 u32     phys_addr32;
257                 u16     gpnv_handle;
258                 u32     access_method_address;
259         };
260         u8      header_format;
261         u8      type_descriptors_supported_count;
262         u8      per_log_type_descriptor_length;
263         u8      supported_log_type_descriptos[0];
264 } __packed;
265
266 #define DMI_SYSFS_SEL_FIELD(_field) \
267 static ssize_t dmi_sysfs_sel_##_field(struct dmi_sysfs_entry *entry, \
268                                       const struct dmi_header *dh, \
269                                       char *buf) \
270 { \
271         struct dmi_system_event_log sel; \
272         if (sizeof(sel) > dmi_entry_length(dh)) \
273                 return -EIO; \
274         memcpy(&sel, dh, sizeof(sel)); \
275         return sprintf(buf, "%u\n", sel._field); \
276 } \
277 static DMI_SYSFS_MAPPED_ATTR(sel, _field)
278
279 DMI_SYSFS_SEL_FIELD(area_length);
280 DMI_SYSFS_SEL_FIELD(header_start_offset);
281 DMI_SYSFS_SEL_FIELD(data_start_offset);
282 DMI_SYSFS_SEL_FIELD(access_method);
283 DMI_SYSFS_SEL_FIELD(status);
284 DMI_SYSFS_SEL_FIELD(change_token);
285 DMI_SYSFS_SEL_FIELD(access_method_address);
286 DMI_SYSFS_SEL_FIELD(header_format);
287 DMI_SYSFS_SEL_FIELD(type_descriptors_supported_count);
288 DMI_SYSFS_SEL_FIELD(per_log_type_descriptor_length);
289
290 static struct attribute *dmi_sysfs_sel_attrs[] = {
291         &dmi_sysfs_attr_sel_area_length.attr,
292         &dmi_sysfs_attr_sel_header_start_offset.attr,
293         &dmi_sysfs_attr_sel_data_start_offset.attr,
294         &dmi_sysfs_attr_sel_access_method.attr,
295         &dmi_sysfs_attr_sel_status.attr,
296         &dmi_sysfs_attr_sel_change_token.attr,
297         &dmi_sysfs_attr_sel_access_method_address.attr,
298         &dmi_sysfs_attr_sel_header_format.attr,
299         &dmi_sysfs_attr_sel_type_descriptors_supported_count.attr,
300         &dmi_sysfs_attr_sel_per_log_type_descriptor_length.attr,
301         NULL,
302 };
303
304
305 static struct kobj_type dmi_system_event_log_ktype = {
306         .release = dmi_entry_free,
307         .sysfs_ops = &dmi_sysfs_specialize_attr_ops,
308         .default_attrs = dmi_sysfs_sel_attrs,
309 };
310
311 typedef u8 (*sel_io_reader)(const struct dmi_system_event_log *sel,
312                             loff_t offset);
313
314 static DEFINE_MUTEX(io_port_lock);
315
316 static u8 read_sel_8bit_indexed_io(const struct dmi_system_event_log *sel,
317                                    loff_t offset)
318 {
319         u8 ret;
320
321         mutex_lock(&io_port_lock);
322         outb((u8)offset, sel->io.index_addr);
323         ret = inb(sel->io.data_addr);
324         mutex_unlock(&io_port_lock);
325         return ret;
326 }
327
328 static u8 read_sel_2x8bit_indexed_io(const struct dmi_system_event_log *sel,
329                                      loff_t offset)
330 {
331         u8 ret;
332
333         mutex_lock(&io_port_lock);
334         outb((u8)offset, sel->io.index_addr);
335         outb((u8)(offset >> 8), sel->io.index_addr + 1);
336         ret = inb(sel->io.data_addr);
337         mutex_unlock(&io_port_lock);
338         return ret;
339 }
340
341 static u8 read_sel_16bit_indexed_io(const struct dmi_system_event_log *sel,
342                                     loff_t offset)
343 {
344         u8 ret;
345
346         mutex_lock(&io_port_lock);
347         outw((u16)offset, sel->io.index_addr);
348         ret = inb(sel->io.data_addr);
349         mutex_unlock(&io_port_lock);
350         return ret;
351 }
352
353 static sel_io_reader sel_io_readers[] = {
354         [DMI_SEL_ACCESS_METHOD_IO8]     = read_sel_8bit_indexed_io,
355         [DMI_SEL_ACCESS_METHOD_IO2x8]   = read_sel_2x8bit_indexed_io,
356         [DMI_SEL_ACCESS_METHOD_IO16]    = read_sel_16bit_indexed_io,
357 };
358
359 static ssize_t dmi_sel_raw_read_io(struct dmi_sysfs_entry *entry,
360                                    const struct dmi_system_event_log *sel,
361                                    char *buf, loff_t pos, size_t count)
362 {
363         ssize_t wrote = 0;
364
365         sel_io_reader io_reader = sel_io_readers[sel->access_method];
366
367         while (count && pos < sel->area_length) {
368                 count--;
369                 *(buf++) = io_reader(sel, pos++);
370                 wrote++;
371         }
372
373         return wrote;
374 }
375
376 static ssize_t dmi_sel_raw_read_phys32(struct dmi_sysfs_entry *entry,
377                                        const struct dmi_system_event_log *sel,
378                                        char *buf, loff_t pos, size_t count)
379 {
380         u8 __iomem *mapped;
381         ssize_t wrote = 0;
382
383         mapped = ioremap(sel->access_method_address, sel->area_length);
384         if (!mapped)
385                 return -EIO;
386
387         while (count && pos < sel->area_length) {
388                 count--;
389                 *(buf++) = readb(mapped + pos++);
390                 wrote++;
391         }
392
393         iounmap(mapped);
394         return wrote;
395 }
396
397 static ssize_t dmi_sel_raw_read_helper(struct dmi_sysfs_entry *entry,
398                                        const struct dmi_header *dh,
399                                        void *_state)
400 {
401         struct dmi_read_state *state = _state;
402         struct dmi_system_event_log sel;
403
404         if (sizeof(sel) > dmi_entry_length(dh))
405                 return -EIO;
406
407         memcpy(&sel, dh, sizeof(sel));
408
409         switch (sel.access_method) {
410         case DMI_SEL_ACCESS_METHOD_IO8:
411         case DMI_SEL_ACCESS_METHOD_IO2x8:
412         case DMI_SEL_ACCESS_METHOD_IO16:
413                 return dmi_sel_raw_read_io(entry, &sel, state->buf,
414                                            state->pos, state->count);
415         case DMI_SEL_ACCESS_METHOD_PHYS32:
416                 return dmi_sel_raw_read_phys32(entry, &sel, state->buf,
417                                                state->pos, state->count);
418         case DMI_SEL_ACCESS_METHOD_GPNV:
419                 pr_info("dmi-sysfs: GPNV support missing.\n");
420                 return -EIO;
421         default:
422                 pr_info("dmi-sysfs: Unknown access method %02x\n",
423                         sel.access_method);
424                 return -EIO;
425         }
426 }
427
428 static ssize_t dmi_sel_raw_read(struct file *filp, struct kobject *kobj,
429                                 struct bin_attribute *bin_attr,
430                                 char *buf, loff_t pos, size_t count)
431 {
432         struct dmi_sysfs_entry *entry = to_entry(kobj->parent);
433         struct dmi_read_state state = {
434                 .buf = buf,
435                 .pos = pos,
436                 .count = count,
437         };
438
439         return find_dmi_entry(entry, dmi_sel_raw_read_helper, &state);
440 }
441
442 static struct bin_attribute dmi_sel_raw_attr = {
443         .attr = {.name = "raw_event_log", .mode = 0400},
444         .read = dmi_sel_raw_read,
445 };
446
447 static int dmi_system_event_log(struct dmi_sysfs_entry *entry)
448 {
449         int ret;
450
451         entry->child = kzalloc(sizeof(*entry->child), GFP_KERNEL);
452         if (!entry->child)
453                 return -ENOMEM;
454         ret = kobject_init_and_add(entry->child,
455                                    &dmi_system_event_log_ktype,
456                                    &entry->kobj,
457                                    "system_event_log");
458         if (ret)
459                 goto out_free;
460
461         ret = sysfs_create_bin_file(entry->child, &dmi_sel_raw_attr);
462         if (ret)
463                 goto out_del;
464
465         return 0;
466
467 out_del:
468         kobject_del(entry->child);
469 out_free:
470         kfree(entry->child);
471         return ret;
472 }
473
474 /*************************************************
475  * Generic DMI entry support.
476  *************************************************/
477
478 static ssize_t dmi_sysfs_entry_length(struct dmi_sysfs_entry *entry, char *buf)
479 {
480         return sprintf(buf, "%d\n", entry->dh.length);
481 }
482
483 static ssize_t dmi_sysfs_entry_handle(struct dmi_sysfs_entry *entry, char *buf)
484 {
485         return sprintf(buf, "%d\n", entry->dh.handle);
486 }
487
488 static ssize_t dmi_sysfs_entry_type(struct dmi_sysfs_entry *entry, char *buf)
489 {
490         return sprintf(buf, "%d\n", entry->dh.type);
491 }
492
493 static ssize_t dmi_sysfs_entry_instance(struct dmi_sysfs_entry *entry,
494                                         char *buf)
495 {
496         return sprintf(buf, "%d\n", entry->instance);
497 }
498
499 static ssize_t dmi_sysfs_entry_position(struct dmi_sysfs_entry *entry,
500                                         char *buf)
501 {
502         return sprintf(buf, "%d\n", entry->position);
503 }
504
505 static DMI_SYSFS_ATTR(entry, length);
506 static DMI_SYSFS_ATTR(entry, handle);
507 static DMI_SYSFS_ATTR(entry, type);
508 static DMI_SYSFS_ATTR(entry, instance);
509 static DMI_SYSFS_ATTR(entry, position);
510
511 static struct attribute *dmi_sysfs_entry_attrs[] = {
512         &dmi_sysfs_attr_entry_length.attr,
513         &dmi_sysfs_attr_entry_handle.attr,
514         &dmi_sysfs_attr_entry_type.attr,
515         &dmi_sysfs_attr_entry_instance.attr,
516         &dmi_sysfs_attr_entry_position.attr,
517         NULL,
518 };
519
520 static ssize_t dmi_entry_raw_read_helper(struct dmi_sysfs_entry *entry,
521                                          const struct dmi_header *dh,
522                                          void *_state)
523 {
524         struct dmi_read_state *state = _state;
525         size_t entry_length;
526
527         entry_length = dmi_entry_length(dh);
528
529         return memory_read_from_buffer(state->buf, state->count,
530                                        &state->pos, dh, entry_length);
531 }
532
533 static ssize_t dmi_entry_raw_read(struct file *filp,
534                                   struct kobject *kobj,
535                                   struct bin_attribute *bin_attr,
536                                   char *buf, loff_t pos, size_t count)
537 {
538         struct dmi_sysfs_entry *entry = to_entry(kobj);
539         struct dmi_read_state state = {
540                 .buf = buf,
541                 .pos = pos,
542                 .count = count,
543         };
544
545         return find_dmi_entry(entry, dmi_entry_raw_read_helper, &state);
546 }
547
548 static const struct bin_attribute dmi_entry_raw_attr = {
549         .attr = {.name = "raw", .mode = 0400},
550         .read = dmi_entry_raw_read,
551 };
552
553 static void dmi_sysfs_entry_release(struct kobject *kobj)
554 {
555         struct dmi_sysfs_entry *entry = to_entry(kobj);
556         sysfs_remove_bin_file(&entry->kobj, &dmi_entry_raw_attr);
557         spin_lock(&entry_list_lock);
558         list_del(&entry->list);
559         spin_unlock(&entry_list_lock);
560         kfree(entry);
561 }
562
563 static struct kobj_type dmi_sysfs_entry_ktype = {
564         .release = dmi_sysfs_entry_release,
565         .sysfs_ops = &dmi_sysfs_attr_ops,
566         .default_attrs = dmi_sysfs_entry_attrs,
567 };
568
569 static struct kobject *dmi_kobj;
570 static struct kset *dmi_kset;
571
572 /* Global count of all instances seen.  Only for setup */
573 static int __initdata instance_counts[MAX_ENTRY_TYPE + 1];
574
575 /* Global positional count of all entries seen.  Only for setup */
576 static int __initdata position_count;
577
578 static void __init dmi_sysfs_register_handle(const struct dmi_header *dh,
579                                              void *_ret)
580 {
581         struct dmi_sysfs_entry *entry;
582         int *ret = _ret;
583
584         /* If a previous entry saw an error, short circuit */
585         if (*ret)
586                 return;
587
588         /* Allocate and register a new entry into the entries set */
589         entry = kzalloc(sizeof(*entry), GFP_KERNEL);
590         if (!entry) {
591                 *ret = -ENOMEM;
592                 return;
593         }
594
595         /* Set the key */
596         memcpy(&entry->dh, dh, sizeof(*dh));
597         entry->instance = instance_counts[dh->type]++;
598         entry->position = position_count++;
599
600         entry->kobj.kset = dmi_kset;
601         *ret = kobject_init_and_add(&entry->kobj, &dmi_sysfs_entry_ktype, NULL,
602                                     "%d-%d", dh->type, entry->instance);
603
604         if (*ret) {
605                 kfree(entry);
606                 return;
607         }
608
609         /* Thread on the global list for cleanup */
610         spin_lock(&entry_list_lock);
611         list_add_tail(&entry->list, &entry_list);
612         spin_unlock(&entry_list_lock);
613
614         /* Handle specializations by type */
615         switch (dh->type) {
616         case DMI_ENTRY_SYSTEM_EVENT_LOG:
617                 *ret = dmi_system_event_log(entry);
618                 break;
619         default:
620                 /* No specialization */
621                 break;
622         }
623         if (*ret)
624                 goto out_err;
625
626         /* Create the raw binary file to access the entry */
627         *ret = sysfs_create_bin_file(&entry->kobj, &dmi_entry_raw_attr);
628         if (*ret)
629                 goto out_err;
630
631         return;
632 out_err:
633         kobject_put(entry->child);
634         kobject_put(&entry->kobj);
635         return;
636 }
637
638 static void cleanup_entry_list(void)
639 {
640         struct dmi_sysfs_entry *entry, *next;
641
642         /* No locks, we are on our way out */
643         list_for_each_entry_safe(entry, next, &entry_list, list) {
644                 kobject_put(entry->child);
645                 kobject_put(&entry->kobj);
646         }
647 }
648
649 static int __init dmi_sysfs_init(void)
650 {
651         int error = -ENOMEM;
652         int val;
653
654         /* Set up our directory */
655         dmi_kobj = kobject_create_and_add("dmi", firmware_kobj);
656         if (!dmi_kobj)
657                 goto err;
658
659         dmi_kset = kset_create_and_add("entries", NULL, dmi_kobj);
660         if (!dmi_kset)
661                 goto err;
662
663         val = 0;
664         error = dmi_walk(dmi_sysfs_register_handle, &val);
665         if (error)
666                 goto err;
667         if (val) {
668                 error = val;
669                 goto err;
670         }
671
672         pr_debug("dmi-sysfs: loaded.\n");
673
674         return 0;
675 err:
676         cleanup_entry_list();
677         kset_unregister(dmi_kset);
678         kobject_put(dmi_kobj);
679         return error;
680 }
681
682 /* clean up everything. */
683 static void __exit dmi_sysfs_exit(void)
684 {
685         pr_debug("dmi-sysfs: unloading.\n");
686         cleanup_entry_list();
687         kset_unregister(dmi_kset);
688         kobject_put(dmi_kobj);
689 }
690
691 module_init(dmi_sysfs_init);
692 module_exit(dmi_sysfs_exit);
693
694 MODULE_AUTHOR("Mike Waychison <mikew@google.com>");
695 MODULE_DESCRIPTION("DMI sysfs support");
696 MODULE_LICENSE("GPL");